Self-flexing finlike structure

ABSTRACT

A finlike structure has a plurality of tubular driving members in an elastomeric matrix biased so that under pressure applied to fluid in the driving members, members of one set of them flex to one side of the structure, and members of another set of them flex to the other side. Pressure is applied to one side or the other, or to both cyclically, to use the structure for various purposes, such as a gate, a valve, a motive device, a rudder or a sculling device.

United States Patent Inventor Stanley R. Rich Woreester, Mm.

Appl. No. 807,649

Filed Mar. 17, 1969 Patented June 22, 1971 Assignees Alfred B. Rosen Newton, Mass.

Leonard L. Krasnaw Worcester, Mas. part interest to each SELF-FLEXING FINLIKE STRUCTURE 19 Claims, 21 Drawing Figs.

U.S.Cl 114/140, 114/39, 114/162, 416/81, 417/436 111t.Cl B63b 3/38, 1363b 35/00 FieldofSeareh 114/140, 162,126; 115/28, 29; 416/81 78, 79, 82; 417/436, 437, 476

[56] References Cited UNlTED STATES PATENTS 3,015,298 1/1962 Bell 611111.... 114/126 3,118,639 1/1964 10661111111 115/29 x Primary Examiner-Trygve M. Blix AttorneyA1fred 1-1. Rosen PATENTED JUH22 IHII SHEET 2 OF 5 Fig. 2

Fig. 8.

A'I'I'ORNI'IY SELF-FLEXING FINLIKE STRUCTURE BACKGROUND OF THE INVENTION Vanelike structures are known which perform the functions of sluice-gates, valves, and rudders for boats. These are rigid devices which are pivotally supported for use, and driven either through the pivot or by way of externally mounted arms cooperating with links or cables. The present invention provides a new structure, more resembling a fin, which can flex in response to the action of internally located motors or flexor members, to perform these and other functions in a new and improved manner. Motor elements of the kinds described in my copending application, Ser. No. 622,183, filed Mar. 10, 1967, can be used, although the present invention is not limited to them. The imparting of motion to a confined fluid, or the propulsion of a boat in water, is made possible without rotating shafts and screws. A finlike structure which can be used as a rudder, a sculling device, or a sculling rudder for a boat is made possible.

DESCRIPTION OF THE INVENTION These and other novel properties of the invention will appear in the following description of exemplary embodiments of it. This description refers to the accompanying drawings, in which:

FIGS. I and 2 show a motor element according to my copending application mentioned above;

FIGS. 3, 3A and 3B are simplified schematic illustrations of motor elements useful in the invention;

FIG. 4 illustrates certain operating properties of such motor elements;

FIG. 5 shows another form of motor element;

FIG. 6 is an end view, partly schematic, of a finlike structure;

FIG. 7 is a section on line 77 of FIG. 6;

FIG. 8 is a section on line 88 of FIG. 7, with some remote parts not shown;

FIG. 9 illustrates the operation of the structure of FIGS. 6, 7 and 8;

FIG. 10 shows a finlike structure according to the invention fitted to a sailboat, for use as a rudder or a sculling device, or both;

FIG. 11 shows a manually powered driving mechanism for the fin of FIG. 10;

FIG. 12 schematically illustrates the installation of the driving mechanism of FIG. 11 in the boat of FIG. 10;

FIG. 13 schematically illustrates the operation of the FIG. 12 installation;

FIG. 14 is a cross section showing a modified finlike structure;

FIG. 15 is a schematic plan view of another embodiment of the finlike structure of the invention;

FIG. 16 shows a power-driven driving mechanism for use in place of that shown in FIG. 11;

FIG. 17 is a modification of FIG. 16, for automatic sculling and manually controlled steering of a boat such as is shown in FIG. 10;

FIG. 18 illustrates how finlike structures of the invention may be combined in multiple sets for cooperating action; and,

FIG. 19 is another embodiment of the finlike structure according to the invention.

DESCRIPTION OF THE DRAWINGS In FIGS. 1 and 2, a tube 10 which may be made of handwrapped india or gum rubber, for example, is fitted with a Iongitudinal restraint member 12 such as a piece of nylon or cotton cord attached to the tube at its outer side running in its axial direction. The restraint member 12 has the property that it is flexible but, compared to the tube 10, is substantially nonextensible; it is attached by a rubber cement or other rubber adhesive to the tube 10. A rubber cement such as Pliobond (Trademark) from Goodyear Rubber Company is suitable. A cord 14, such as nylon or cotton cord, is helically wrapped tightly around the tube 10 and longitudinal restraint member 12 until the tube 10 is substantially entirely wrapped helically. This helical winding 14 is also bonded to the tube 10 like the restraint member tube 12. The resultant motor element or flexor unit 15 is capable of longitudinal elongation except where restrained by the longitudinal restraint member 12. The helically wrapped cord member 14 provides restraint against radial expansion or distortion of the tube 10, while permitting its longitudinal expansion.

The motor element 15 is used by inserting a plug 16 in one end and providing at the other end a conduit 18 serving as a passage to the interior of the tube 10 for a fluid under pressure. The tube 10 thus encloses a fluid-confining space. It is preferred to use a noncompressible fluid, such as a liquid, to operate the motor element 15.

FIGS. 3, 3A and 3B symbolically represent a motor element 15, in longitudinal section and cross section respectively. In FIG. 3, which is a longitudinal section, the motor element is represented by a tube 20 having a restraint member 22 along one side and a closure 24 at one end. An arrow 26 is shown at the open end 28 which is the passage for introducing and removing a fluid under pressure from the fluid-confining space in the tube. FIG. 3A represents a cross section of the tube 20 with the restraint member 22 along one side (bottom in FIG. 3A), while FIG. 38 represents a cross section of the tube 20 with the restraint member 22 along the opposite side (top in section 38). These symbolic representations of a motor element 15 will simplify the illustration of the descriptions of embodiments which follow. They should be regarded in a generic sense, and not as limited to the structure of FIGS. 1 and 2. While radial distortion restraint means, such as the helically wrapped cords 14 in FIG. I, are not shown, the same or equivalent will, of course, be present in practice; see, for example, FIG. 19.

FIG. 4 illustrates the general principle of operation of the motor element 15 in FIG. 1, when pressure in excess of ambient pressure is applied to a fluid contained in its fluid-confin ing space. The symbolic representation of FIG. 3 is employed. Assuming the length of the motor element to be I in the relaxed or unflexed state, the outer surface of the motor element furthest removed from the longitudinal restraint member 22 stretches or elongates a distance =Al, and assumes the length l+Al, when pressure in excess of ambient pressure is applied on fluid therein through passage 28. The longitudinal restraint member 22 biases the motor element to flex in a prescribed direction when such pressure is applied. Under the condition that the motor element 15 has elastic properties which are uniform along its length I when it is made by fluid pressure to flex from a straight to a curved posture as shown in FIG. 4, the longitudinal restraint member 22 describes the arc of a circle so that I=Ra where R is the radius of the circle and 01" is the angle of the arc.

Similarly:

H-Al=a(R+d) where d" is the diameter of the motor element 15.

Where a=l radian: H-Al=R+d and Al=d This relationship enables the computation of the amount of a noncompressible fluid that must be added to a given motor element that is full of the fluid but undeflected, in order to achieve a known deflection that will provide an angle a=l radian.

In the flexed state under fluid pressure in excess of ambient, the motor element 15 is restrained from radial expansion or distortion by the circumferentially wrapped cords 14. The tubular structure 10 can change its longitudinal dimension parallel to its longitudinal axis everywhere except where restrained by longitudinal restraint member 12. When the fluid under excess pressure is released from the motor element, it returns to its relaxed or undeflected state due to the elasticity of the underlying tubular member 10.

FIG. 5 illustrates how the basic flexor unit or motor element can be made to flex nonuniformly. As shown in FIG. SA, a motor element 35 is made of a tubular element 30 surrounding a fluid-confining space 32 of cross section which is uniform with respect to the longitudinal axis, closed at one end 34 and open at the other end 36 to provide a passage for fluid. The longitudinal restraint member 38 is applied to a side 39 of the tube 30 having a thickness which is not uniform with respect to location along the axis of the tube. Thus, near the open end, or passage 36, this side 39 is thicker than near the closed end 34, and the thickness tapers rapidly toward the intermediate region 37 of the tube, and then is more nearly uniform from the intermediate region to the closed end 34. The result of this construction is that the motor element 35 will flex sharply about the intermediate region 37 as shown in the dotted line representation in FIG. 5B, when fluid under pressure in excess of ambient is introduced into the fluid-confining space 32.

FIGS. 6, 7 and 8 show how a plurality of basic motor elements or flexor units, such as elements or 35, can be combined in a single structure, comprising an interdigital array of oppositely biased units or elements in a structure which in the relaxed state has a configuration lying in a neutral position, which may be (as illustrated) a plane, and which can be made, under pressure applied to fluid means in the fluid-confining spaces of the individual elements, to flex out of the neutral position. This structure has utility as a gate, a valve, a motive device for applying power to move a fluid in which it may be immersed, or when installed in a boat as a rudder, a sculling device or a combined rudder and sculling device. In these figures motor elements, SI, 52, 53, 56, 55, 56, 57 and 58 are arrayed side by side with their longitudinal axes parallel, enveloped in an elastomeric matrix 50. Each element has a longitudinal restraint member 51' to 58' respectively. As shown more fully in FIG. 8, the restraint members 51', 53', 55' and 57' are all oriented to one side of their respective motor elements 51, 53, 55 and 57, while the restraint members 52, 54, 56' and 58 are all oriented to the opposite side of their respective motor elements 52, 54, 56 and 58. Moreover, the odd-numbered motor elements are interdigitally arranged between the even-numbered motor elements, the odd-numbered set being designated Set I, and the even-numbered set being designated Set II, as best shown in FIG. 8.

In FIGS. 6 and 7, a plenum conduit 62 is shown coupled to the odd-numbered motor elements of Set I, and in FIG. 6 a plenum conduit 64 is shown, this latter conduit being coupled to the even-numbered motor elements of Set II.

Plenum conduit 62 is coupled to the motor elements of Set I via coupling pipes 5L1, 53.1, 55.1 and 57.1. Plenum pipes 52.1, 54.I, 56.l and 58.1 serve to couple plenum conduit 64 to the motor elements of Set II. The elastomeric matrix 50 has a smooth outer skin which tapers gradually toward the free end 63 and can, if desired, be extended some distance beyond the ends of the motor elements which are confined within it, as is described more particularly with reference to FIG. 15.

The structure shown in FIGS. 6, 7 and 8 is finlike in nature, and has a prescribed neutral configuration, here shown as planar, when it is in the relaxed state. When fluid under pressure in excess of ambient is introduced via plenum conduit 64 to the fluid-confining spaces of motor elements Set II, this structure will flex to one side of the relaxed plane as is represented in FIG. 9A, where the fin is schematically represented as a smoothly tapering body 66 with a restraint member 65 representing members 52', 54, 56' and 58' in FIG. 7 along one side. If, on the other hand, fluid under excess pressure is introduced via plenum conduit 62 to the fluid-confining spaces of the motor elements in Set I, the fin will flex in the opposite direction as shown in FIG. 9B in which a restraint member 67 represents the restraint members 51 53', 55' and 57' of that set. If fluid under the same pressure is introduced into both conduits, the fin will flex to one side or the other, depending upon which is the greater pressure.

vFIG. 10 shows a sailboat to which a rudder 70 according to the present invention has been fitted. Only the plenum conduit 72 and motor elements 73, 74, 75 and 76 of Set I which are coupled to it are indicated in FIG. 10, but it will be understood that the plenum conduit and motor elements of Set II are also present. FIG. 12 schematically shows a plenum conduit 78 for the motor elements of Set II. The rudder is shown attached to the keel 80 of a sailboat 82. A suitable mode of attachment is illustrated in FIG. 112 where the matrix of the rudder 70 is shown extending over the after-edge of the keel on both sides 84 and 85, and smoothly fairing into the keel 80. The plenum conduits 72 and 78 can be and in practice are preferably concealed within the keel 80, or some other part of the boat 82, and they are shown mounted externally in the drawings to simplify the illustration.

FIGS. II and I2 illustrate one way to employ the rudder 70 to steer or to skull the boat 82, or both. A chamber 88 fitted with a piston 90 between two conduits 92 and 94 is coupled via these conduits to the plenum conduits 72 and 78, respectively. As shown in FIG. 12, this arrangement provides a closed system which consists of the chamber 88, conduits 92 and 94, plenum conduit 72 and 78, fluid-confining spaces of the motor elements in the rudder 70 and pipes connecting between those spaces and their respective plenum conduits, which can be filled with a fluid. Preferably a noncompressive fluid such as hydraulic oil of a suitable grade (not shown) fills this entire system. Then, as the piston 90 is moved to one side where it is nearer one conduit than the other, the fluid pressure is increased on that side and decreased on the other side. For example, if the piston 90 is moved closer to the conduit 92 for motor elements Set I, the fluid pressure on motor elements Set I becomes greater than the fluid-pressure on motor elements Set II, and vice versa. A lever 96 which conveniently may be the tiller of the boat 82 is attached by a link 98 to the piston 90 and by moving the lever 96 about its pivot point 99, the piston 90 may be moved toward one end of the other in the chamber 88.

FIG. 13 shows schematically how the tiller may be used to steer the boat 82. In this figure lines represent the positions of the various elements described. Thus, if the tiller 96 is moved to the left as shown in FIG. 13A, the rudder 70 may, for example, flex to the right (looking aft) relative to the keel 80; and if the rudder is moved to the right as shown in FIG. 138, the rudder will then flex or bend in the opposite direction. Clearly the direction of rudder response may be chosen by connecting conduits 92 and 94 to the appropriate parts of the chamber 88. What is important to realize is that the invention has provided a smoothly faired self-flexing rudder for a sailboat or the like, which can be controlled very simply by a device resembling in all respects a tiller having a well-known form.

By moving the tiller back and forth between the positions shown in FIGS. ISA and 138, the rudder may be made to execute an oscillating motion back and forth about the keel 8t), and this motion will skull the boat 82 through the water. The invention is seen to have the properties of a sculling device, or a rudder, or a sculling rudder.

A rudder or sculling device according to the invention can be provided not only with motor elements to flex it for steering or skulling purposes, but also with additional motor elements for the purposes of trimming as may be useful in sailing. FIG. 14 shows an appropriate arrangement. In FIG. 14, the rudder plenum 102 incorporates Sets I and II of motor elements for sculling, or steering, or, if desired, combined steering and sculling purposes, and Sets I" and II" of motor elements for trimming purposes. The first sets of motor elements I and II will be connected to motive means such as is shown in FIGS. 11 and 12, or FIG. 16 or FIG. 17 (to be described). The second Sets I" and II" of motor elements may be connected to a source or sources (not shown) of fluid under pressure other than the motive means, for warping or bending one portion 104 of the rudder with respect to the remainder, and these pressures can be maintained constant or varied as desired independently of the steering or sculling pressures.

FIG. 15 illustrates another embodiment of the invention which is highly useful for sculling purposes. In this figure a fin 110 is represented by a dashed outline and Set I only of motor elements 111, 112, 113 and 114 are schematically represented connected to a Set I plenum conduit 116. In the plenum conduit, between each adjacent pair of motor elements in Set I, a constriction 117, 118 or 119 is fitted. These constrictions provide that as fluid pressure is introduced into the plenum conduit 116, the maximum pressure will appear first at the first member 111 of Set I and then at the second member 112, and then at the third member 113 and, finally at the last, or most remote member 114 of the set. A similar treatment is applied to the Set II motor elements (not shown). This constriction results in a compound flexural motion of the fin 110 when pressure in excess of ambient is applied alternatingly via one conduit then the other, to a fluid in the rudder 110. One side. for example, at the top edge, begins to flex first, and the flcxure gradually proceeds in a wave to the lower edge, so that the fin flexes with a wavy motion, first to one side, then to the other, of its neutral position.

As is further shown in FIG. 15, the fin plenum itself can extend a substantial distance beyond the closed ends of the motor elements 111-114, inclusive, so that a wavy motion is generated from the forward to the aft edge of the fin when it is used as a sculling device. This feature may be used independently of the constrictions l17119.

The device shown in FIG. is aptly termed a soft" sculling fin, more nearly representing a natural fin of a fish, as distinguished from a comparatively hard rudder or sculling fin.

While up to this point the invention has been described in connection with its uses as a fin or a sculling rudder, it will be appreciated that the fin structure shown in FIGS. 6-8 inclusive, may be mounted on a vessel in a position where it can act as a stabilizing fin to stabilize roll or to stabilize pitch. For stabilizing roll the fin can be mounted in a plane which lies between horizontal and nearly vertical like a bilge" keel, with its root forward and its flexing end extending aft, so that its flexure can compensate for roll in response to a sensing device such as a clinometer. For stabilizing pitch, the fin can be mounted in a horizontal posture on a forward part of the vessel and its flexure can be made responsive to a pitch sensing device. In either case, fins for these purposes will be mounted on both sides of the vessel.

FIG. 16 illustrates a power-driven hydraulic steering system which might be used in place of the manually powered system shown in FIGS. 11 and 12. A fin according to FIG. 7, for example, (not shown) will be coupled to plenum conduits 132 and 134. A gear pump 120 provides fluid under pressure at its output conduit 122, and fluid returns to the pump at a return conduit 124. A two-way valve 123, of a kind which is well known, has a piston 128 in a chamber 130. The pump output conduit 122 is coupled as a feed conduit to the chamber between the plenum conduits 132 and 134 for motor element Sets I and II, respectively, and the piston serves to direct fluid from the feed conduit 122 to one or the other of these two plenum conduits. When the piston is in the location shown in solid line, fluid under high pressure from the pump goes from conduit 122 to conduit 134 for motor elements Set II, and fluid from conduit 132 goes to return conduit 124 via a coupling conduit 125. When the piston is moved to an alternative location 135 shown in dotted line, fluid from the pump output conduit 122 is passed to plenum conduit 132 for motor elements Set I and fluid from motor elements Set 11 is exhausted from their plenum conduit 134 to pump return conduit 124 via a second coupling conduit 126. The tiller 96 is used via a link 136 to move the piston 128 to a desired position between its limits and in this way the tiller serves merely to control the application of pressure from the pump 120 to a fluid present in the motor elements Sets 1 and II of a flexible fin which is coupled to the system. Clearly, when a fin is coupled to it, the system of FIG. 16 like the system of FIG. 12 comprises a closed hydraulic system which initially is filled with a suitable noncompressive fluid, and the tiller 96 can control the attitude of the fin.

While the system of FIG. 16 can be used for sculling, in the same manner as the system of FIG. 12, and the amount of force applied to flex the fin which is coupled to it will depend upon the magnitude of the pressure supplied by the pump 120, the system can, if desired, be automated for sculling purposes. FIG. 17 shows a system which is designed for both automated sculling and manually controlled steering. This figure is a modification of FIG. 16 in which the pump is omitted from the illustration. In FIG. 17 the valve 123 is fitted with a mechanism for oscillating its piston back and forth continuously between two extreme positions. The mechanism 140 is illustrated as a round member rotatable in the direction of the arrow 142 on an axle 146 to which the link 136 of the piston 128 is connected at a pivot 144 located near the periphery of the round member 140. A pair of pressure-regulating valves 152 and 154 are fitted in the return coupling conduits 125 and 126, respectively. A lever 156 pivoted around the pivot 157 is connected to these valves by links 158 and 159 on opposite sides of the pivot 157. As the lever 156 is moved about its pivot 157, it will close one valve and open the other, relatively speaking. In a neutral position which is illustrated in FIG. 17, the valves 152 and 154 are equally open and, therefore, do not effect a difference in the fluid pressures returned via the coupling conduits 125 and 126. However, if the lever is moved to the left (in FIG. 17) it will close valve 154 and open valve 152, relative one to the other, thereby increasing the pressure in return coupling conduit 126 relative to that in return coupling conduit 125. The effect of this will be to raise the average pressure on fluid in the motor elements of Set 11 as compared to that on fluid in the motor elements of Set I. The opposite will happen if the lever is moved to the right of its neutral position shown in FIG. 17. Thus, a fin driven by the motor system illustrated in FIG. 17 will automatically scull the vessel in which it is installed under drive from the pump P, and if the lever 156 is moved to one side or the other of its neutral position, the fin will also steer the vessel. The lever 156 is thus the tiller of the vessel.

Fins of the invention may be combined in pairs as shown in FIG. 18, where fins 162 and 164 are represented. An advantageous mode in which to employ such pairs of fins is to drive them in a sculling fashion in a clap-hands mode, so that they flex toward each other, and then away from each other. This can be done by applying the high pressure to fluid in motor elements of Sets I via conduits 163 and 165 together, and then to fluid in motor elements of Sets II via conduits 167 and 169 together, it being understood that the restraint members of the motor elements are so arrayed that when the higher pressure is on fluid in motor elements of Sets I the rudders 162 and 164 will flex toward each other, and when the higher pressure is on fluid in the motor elements of Sets II the rudders will flex away from each other. Such fin pairs can be used to propel a fluid relative to its container, as well as to propel a boat through the water, or to stabilize or maneuver it.

FIG. 19 shows another embodiment of the fin similar to FIG. 7 except that the motor elements, or flexor units, are made of metal bellows with longitudinal restraint members externally applied. An elastomeric matrix 170 envelopes an interdigital array of oppositely biased motor elements 181, 182, 183, 184, 185, 186, 187 and 188. The odd-numbered members of this group, forming Set I, have their longitudinal restraint members 181', 183', 185 and 187' all located to one side of the array, biasing the motor elements of Set I for flexure to one side of the neutral posture of the fin, while the even-numbered members of the group, forming Set I, have their longitudinal restraint members (not shown) all located to the other side of the array, biasing the motor elements of Set 11 for flexure to the other side of the neutral posture of the fin. The plenum conduit 172 for Set I is shown coupled via pipes 181.1, 183.1, 185.1 and 187.1 to the motor elements of Set I. The coupling pipes 182.1, 184.1, 186.1 and 188.1 couple the motor elements of Set II to a plenum chamber (not shown) for Set 11. The fin shown in FIG. 19 operates in the same manner as the fin shown in FIG. 7, and its characteristics may be similarly varied. The two fins differ essentially only in the metal bellows used for the motor elements in FIG. 19. The restraint members may be wires attached to the bellows as by weldings. Restraint against radial distortion may be inherent in the material of which the bellows are made; however, additional such restraint can be added if needed.

The motor elements are not necessarily bound in the elastomeric matrix of, for example, FIG. 7 or FIG. 19, but may be free to slip or slide relative to the adjacent envelope, in a direction parallel with their own longitudinal axes. It will be noted that in FIG. 19 the matrix 170, where shown in section, is behind the motor elements, not necessarily tightly encapsulating them. Also-in FIGS. 1 and 19, while for simplicity of illustration the restraint members have been shown outside the motor elements, they may be placed inside, or in FIG. 1 actually molded into the wall of the tube 10. While the foregoing description has stated the desirability of using a noncompressible fluid in the motive systems of the exemplary embodiments gases, and vapors such as steam, may be used under appropriate circumstances, in other embodiments of the inven tion, as where it is desired to use a steam boiler as a source of energy. Although the method for automatic sculling described in connection with FIG. 17 employs an oscillating valve externally driven by a rotating member, this again is for simplicity of illustration. Obviously, commercially available self-oscillating four-way valves can be utilized for this purpose. It is, therefore, intended that the claims which follow are not limited to the details of the exemplary embodiments of the invention which have been described.

lclaim:

l. A self-flexing structure having in combination a plurality of actuating units, each unit comprised of an elongated hollow tube having elastic walls enclosing a fluid-confining space and a passage communicating with said space for introducing fluid into and removing fluid from said space, said tube having the property that it flexes to bend its longitudinal axis in a prescribed direction responsive to pressure exerted on a fluid when present in said space, said structure comprising at least a first and a second of said units disposed in substantially sideby-side parallelism, and means connecting said units together so that if one unit flexes it will pull the other with it to flex similarly, said prescribed directions being differently oriented relative one to the other.

2. A self-flexing structure according to claim l in which said units are disposed side-by-side in a substantially planar configuration with the longitudinal axes of said units substantially parallel to each other and to the plane of said configuration when all of said units are not flexed, and said prescribed directions are oriented oppositely to each other and transversely to the plane of said configuration.

3. A self-flexing structure according to claim 2 having a first set of said first units, and a second set of said second units, members of said first set being arrayed interdigitally with members of said second set in said configuration, first conduit means interconnecting said passages of said first units, and second conduit means interconnecting said passages of said second units.

4. A self-flexing structure according to claim ll having means coupled to each of said passages for applying pressure on a fluid when present in the space with which the passage communicates.

5. A structure according to claim 4 in which the pressureapplying means incorporates a control member for applying at said passages, selectively, like pressures, or pressures which are greater at one passage than at the other.

6. A structure according to claim 5 including means to vary said pressures cyclically about a prescribed reference pressure.

7. A self-flexing structure according to claim 2 combined with a boat, said structure being attached as a rudder to said boat with said plane substantially in the rudder amidships position, first conduit means connecting to said passage of each first unit, second conduit means connecting to said passage of each second unit, means coupled to each of said conduit means for applying pressure on a fluid when present therein, said pressure-applying means incorporating a control member for applying at said conduit means, selectively, like pressures, or pressures which are greater at one of said conduit means than at the other.

8. A combination according to claim 7 in which said control member is the tiller of said boat.

9. A combination according to claim 7 in which said boat has a keel and said structure is attached to the after edge of said keel forming a smooth continuation of said keel.

10. A self-flexing structure according to claim 3 in which said passages of said first units are connected in parallel to said first conduit means, and said passages of said second units are connected in parallel to said second conduit means, and having a constriction in each of said passages, whereby when fluid means is present in said spaces of said units, said passages and said conduit means, a pressure applied at one end of either of said conduit means will become apparent earlier on the fluid means in the nearer of the units connected thereto than on the fluid means in the farther of said units.

ll. A self-flexing structure according to claim 2 having a first set of said first units, and a first set of said second units, members of said first units of said first set being arrayed interdigitally with members of said second units of said first set, first conduit means interconnecting said passages of said first units of said first set, and second conduit means interconnecting said passages of said second units of said first set; a second set of said first units, and a second set of said second units, members of said first units of said second set being arrayed interdigitally with members of said second units of said second set, third conduit means interconnecting said passages of said first units of said second set, and fourth conduit means interconnecting said passages of said second units of said second set.

112. A self-flexing structure according to claim 3 including at least one first unit and one second unit additional to the members of said respective first and second sets.

13. A combination according to claim 7 in which said selfflexing structure includes at least one first unit and one second unit additional to the respective first and second units which are connected to said first and second conduit means, and separate pressure-applying means for applying to said additional units at their respective passages, on fluid when present therein, pressures for trimming said rudder.

M. A self-flexing structure according to claim 2 combined with a boat, said structure being attached as an orientation control member to said boat with said plane substantially in a neutral position, first conduit means connecting to said passage of each second unit, means coupled to each of said conduit means for applying pressure on a fluid when present therein, said pressure-applying means including a control member for applying at said conduit means, respectively, pressures which are alike or which are greater at one of said conduit means than at the other.

15. A combination according to claim 14 in which said neutral position lies in a range from horizontal to approximately vertical, said control member is responsive to the roll of said boat, and said structure is flexible in directions to compensate for said roll when said boat is under way.

16. A combination according to claim 114 in which said neutral position is approximately horizontal, said control member is responsive to the pitch of said boat, and said structure is flexible in directions to compensate for said pitch when said boat is under way.

17. In combination a pair of self-flexing structures according to claim 2 disposed side-by-side in spaced-apart relation with said planes of each at least approximately parallel to each other and means to cause said structures to flex toward and away from each other in a clap-hands mode.

18. The combination of claim 17 attached below the water line to the hull of a boat, means to supply fluid under pressure to said combination and means to control said fluid to cause said structures to flex in said mode, for propelling said boat in a desired direction.

19. A self-flexing structure according to claim 2 combined with a boat, said structure being attached to said boat, first second unit, means coupled to each of said conduit means for applying pressure on a fluid when present therein, said pressure-applying means incorporating means for applying at said conduit means cyclically varying pressures which are in opconduit means connecting to Said passage f each fi t unit, 5 posite phase at one of said conduit means relative to the other.

second conduit means connecting to said passage of each "H050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 305851957 Dated June 22, 197].

Inventor(s) STANLEY R- RICH It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 14, line 52, after "each" (first occurrence) insert --first unit, second conduit means connecting to said passage of each-- Signed and sealed this 2nd day of November 1971.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Acting Commissioner of Patents 

1. A self-flexing structure having in combination a plurality of actuating units, each unit comprised of an elongated hollow tube having elastic walls enclosing a fluid-confining space and a passage communicating with said space for introducing fluid into and removing fluid from said space, said tube having the property that it flexes to bend its longitudinal axis in a prescribed direction responsive to pressure exerted on a fluid when present in said space, said structure comprising at least a first and a second of said units disposed in substantially side-by-side parallelism, and means connecting said units together so that if one unit flexes it will pull the other with it to flex similarly, said prescribed directions being differently oriented relative one to the other.
 2. A self-flexing structure according to claim 1 in which said units are disposed side-by-side in a substantially planar configuration with the longitudinal axes of said units substantially parallel to each other and to the plane of said configuration when all of said units are not flexed, and said prescribed directions are oriented oppositely to each other and transversely to the plane of said configuration.
 3. A self-flexing structure according to claim 2 having a first set of said first units, and a second set of said second units, members of said first set being arrayed interdigitally with members of said second set in said configuration, first conduit means interconnecting said passages of said first units, and second conduit means interconnecting said passages of said second units.
 4. A self-flexing structure according to claim 1 having means coupled to each of said passages for applying pressure on a fluid when present in the space with which the passage communicates.
 5. A structure according to claim 4 in which the pressure-applying means incorporates a control member for applying at said passages, selectively, like pressures, or pressures which are greater at one passage than at the other.
 6. A structure according to claim 5 including means to vary said pressures cyclically about a prescribed reference pressure.
 7. A self-flexing structure according to claim 2 combined with a boat, said structure being attached as a rudder to said boat with said plane substantially in the rudder amidships position, first conduit means connecting to said passage of each first unit, second conduit means connecting to said passage of each second unit, means coupled to each of said conduit means for applying pressure on a fluid when present therein, said pressure-applying means incorporating a control member for applying at said conduit means, selectively, like pressures, or pressures which are greater at one of said conduit means than at the other.
 8. A combination according to claim 7 in which said control member is the tiller of said boat.
 9. A combination according to claim 7 in which said boat has a keel and said structure is attached to the after edge of said keel forming a smooth continuation of said keel.
 10. A self-flexing structure according to claim 3 in which said passages of said first units are connected in parallel to said first conduit means, and said passages of said second units are connected in parallel to said second conduit means, and having a constriction in each of said passages, whereby when fluid means is present in said spaces of said units, said passages and said conduit means, a pressure applied at one end of either of said conduit means will become apparent earlier on the fluid means in the nearer of the units connected thereto than on the fluid means in the farther of said units.
 11. A self-flexing structure according to claim 2 having a first set of said first units, and a first set of said second units, members of said first units of said first set being arrayed interdigitally with members of said second units of said first set, first conduit means interconnecting said passages of said first units of said first set, and second conduit means interconnecting said passages of said second units of said first set; a second set of said first units, and a second set of said second units, members of said first units of said second set being arrayed interdigitally with members of said second units of said second set, third conduit means interconnecting said passages of said first units of said second set, and fourth conduit means interconnecting said passages of said second units of said second set.
 12. A self-flexing structure according to claim 3 including at least one first unit and one second unit additional to the members of said respective first and second sets.
 13. A combination according to claim 7 in which said self-flexing structure includes at least one first unit and one second unit additional to the respective first and second units which are connected to said first and second conduit means, and separate pressure-applying means for applying to said additional units at their respective passages, on fluid when present therein, pressures for trimming said rudder.
 14. A self-flexing structure according to claim 2 combined with a boat, said structure being attached as an orientation control member to said boat with said plane substantially in a neutral position, first conduit means connecting to said passage of each second unit, means coupled to each of said conduit means for applying pressure on a fluid when present therein, said pressure-applying means including a control member for applying at said conduit means, respectively, pressures which are alike or which are greater at one of said conduit means than at the other.
 15. A combination according to claim 14 in which said neutral position lies in a range from horizontal to approximately vertical, said control member is responsive to the roll of said boat, and said structure is flexible in directions to compensate for said roll when said boat is under way.
 16. A combination according to claim 14 in which said neutral position is approximately horizontal, said control member is responsive to the pitch of said boat, and said structure is flexible in directions to compensate for said pitch when said boat is under way.
 17. In combination a pair of self-flexing structures according to claim 2 disposed side-by-side in spaced-apart relation with said planes of each at least approximately parallel to each other and means to cause said structures to flex toward and away from each other in a clap-hands mode.
 18. The combination of claim 17 attached below the water line to the hull of a boat, means to supply fluid under pressure to said combination and means to control said fluid to cause said structures to flex in said mode, for propelling said boat in a desired direction.
 19. A self-flexing structure according to claim 2 combined with a boat, said structure being attached to said boat, first conduit means connecting to said passage of each first unit, second conduit means connecting to said passage of each second unit, means coupled to each of said conduit means for applying pressure on a fluid when present therein, said pressure-applying means incorporating means for applying at said conduit means cyclically varying pressures which are in opposite phase at one of said conduit means relative to the other. 